Lanus overcame Estudiantes 2-1 on Saturday night to claim their third win from five Apertura games and go top of the table.
Gabriel Schurrer's side took a 14th-minute lead through Mario Regueiro, but Mariano Gonzalez drew Estudiantes level in the 28th minute.
Lanus were not held for long though as Silvio Romero restored their one-goal advantage a minute later.
Like Lanus, second-placed Racing Club are unbeaten after five matches, claiming their third draw of the campaign in a stalemate with All Boys.
The men from Avellaneda drew despite the 72nd-minute dismissal of Matias Martinez.
Godoy Cruz were 2-1 winners at Arsenal, with goals from Alvaro Navarro (53) and substitute Ruben Ramirez (90) putting them in control before Mauro Obolo pulled one back in injury time.
